Port forward only working via public IP

[emsbro100]

Hi, I've been trying to get port forwarding working for my Plex server (temporarily my windows machine). I finally got ddns setup with my domain so I can reliably access my home network remotely via Wireguard, and I setup ddns on my Plex server as well to update another of my domains with the public IP of the server so I can reliably access that remotely too, but the port forward rule isn't functioning as expected.

Note: I am behind CGNAT so my VPN and Plex use exclusively IPv6.

The problem is that the port forward rule only works when the redirect target IP is the public IP of the server, rather than the local IP or the alias I have set to the local IP. I've tried adding plex.direct in private domains for Unbound DNS, changing the redirect target IP to the local IP of the server, and changing the destination to the local IP of the server and a few other options, none have worked. This is the only configuration that works but it seems wrong to have the public IPv6 as the redirect target IP rather than the local IPv6. I have the rule shown in the attachment with the public IP blacked out for privacy, but it is most definitely the public IP.

I've tried reading the documentation and looking at guides over and over and I thought I understood what I was doing but I guess not. Any guidance would be greatly appreciated.

[Isabella Borgward]

This might be what you want:

https://docs.opnsense.org/manual/how-tos/nat_reflection.html

but this puzzles me:

the port forward rule only works when the redirect target IP is the public IP of the server

Where are you trying to access this from? If it's from outside your network then that's normal, right?
If it's from inside, then NAT reflection *or* use DNS to handle this scenario.